Periodontal diseases are thought to be infectious diseases caused by bacteria present in dental plaques. Removal of dental plaques is highly important for the health of oral cavities. Tooth brushing is a highly effective method to remove dental plaque from the teeth. Power toothbrushes can enhance the removal of dental plaque. Such power toothbrushes have a set of bristles attached to a brush head which is moved by a driver that causes the bristles to scrub dental surfaces.
Bristles need to be secured in a brush head in a method that keeps them secured in the brush head during use, but provides flexibility for the bristles while brushing. Anchor-free tufting of bristles provides greater flexibility. However, with anchor-free tufting, the bristle tuft can be or become loose within the brush head and the bristles might not always be positioned at an angle optimal for brushing. This is especially true with the motion of power toothbrushes. Further, the process of organizing the bristles into tufts and then forming the brush head material can be time-consuming and expensive.
In addition, the teeth and gums are a complex shaped surface, with significant curvature and variation between individuals. Cleaning plaque efficiently from all surfaces is the goal of oral care, but is particularly difficult from the regions where teeth meet, or along the gum line. Achieving good cleaning is a key goal of toothbrush head design. In certain examples some groups of bristles in the brush head are longer than the rest of the bristles, so that they can access the interproximal spaces better. In the Philips Adaptiveclean brush head, groups of bristles are mounted in an elastomer to provide an ability to flex more than traditional brush heads, to allow adaptation to the underlying contours in the mouth.
A further consideration is the length of the bristles. In particular, the bristle length in a toothbrush is a compromise; longer bristles allow more splaying over the topography of the teeth. However longer bristles also make the brush head bulkier and harder to manoeuvre in the mouth, resulting in difficulty accessing some areas of the teeth. The bristle length chosen is a compromise of these and other factors.
Bristles clean effectively over a certain range of contact forces. If the bristles do not make contact with the surface of the teeth (i.e. the contact force is too low), then cleaning efficiency is far lower than if in contact. A contact force that is too low will not penetrate the plaque, while a contact force that is too high may result in the bristles becoming stationary on the surface of the tooth or gum due to friction forces between the end of the bristles and the tooth or gums exceeding lateral forces (i.e. forces that aim to move the bristles across the teeth), which also leads to ineffective plaque removal. The properties of the elastomer in the Philips Adaptiveclean brush head is a necessary compromise between being soft enough to provide some conformation to the tooth surface, while being firm enough to transmit the lateral forces needed to sweep the bristles.
Accordingly, there is a need in the art for improved brush head assemblies, and methods of their manufacture, that increase the retention of the bristles on the brush head while still providing for flexibility of the bristles during use, and therefore improving oral care.
As noted above there is also, or alternatively, a need in the art for brush head assemblies, and methods of their manufacture, that improve the conformity of the brush head to the tooth and/or gum topography while improving the transmission of lateral forces needed to sweep the bristles.